Tool mounting



AGENT m T N E V W 3 Sheets-Sheet 1 N. w. DENSMORE TOOL MOUNTING FIG. 2.

Aug. 10, 1965 Original Filed April 11, 1958 E m S N E D W L A E m...

Aug. 10, 1965 N. w. DENSMORE TOOL MOUNTING 3 Sheets-Sheet 2 OriginalFiled April 11, 1958 FIG. 5.

84 22 INVENTOR:

NEAL w DENSMORE AGENT Aug. 10, 1965 N. w. DENSMORE TOOL MOUNTING 3Sheets-Sheet 3 Original Filed April 11, 1958 FIG. 6.

FIG. 7.

FIG. 8.

INVENTORZ NEAL W DENSMORE United States Patent 3,199,611 TOQL MQUNTENGNeal W. Densmore, ranklin, P2,, assignor to Joy Manufacturing Company,Pittsburgh, Pin, a corporation of Pennsylvania Continuation ofapplication Ser. No. 727,808, Apr. 11,

1958. This application Aug. 23, 1961, Ser. No.

Claims. (Cl. 17324) This application is a continuation of applicationSerial No. 727,888, filed April 11, 1958, now abandoned.

This invention relates to a tool mounting apparatus and moreparticularly to a mounting means which permits the operation of a mineroof drilling tool, mounted on a self-propelled support, during suchtime when such support performs its function of removing mineral from asolid vein.

Roof conditions in some mines necessitate roof bolting because certainrock strata, forming the roof of the mine, areincompetent to supporttheir own weight after the removal of the mineral thereunder.Incompetent roof strata can be supported by roof bolts securing theincompetent strata to overlying competent strata. Each roof bolt isprovided with a bearing plate between the head of the bolt and the roofof the mine and is threadedly engaged with an expansible nut anchored inthe competent strata.

A roof bolting drill such as that described in US. Patent 2,741,461,adapted to the formation of substantially vertical bores in the roof ofa mine and to the application of rotative forces (wrenching) to the roofbolt, is used in the roof bolting operation. Such operation comprisesthe following steps: a substantially vertical bore is formed in the roofof the rrnne by the aforementioned apparatus and extends through theroof strata of the mine into overlying competent strata; an elongatedroof bolt, provided with an expansible nut on its threaded end and aroof bearing plate adjacent the head end is inserted in the bore in suchmanner that the expansible nut is positioned within the competentstrata; wrenching action applied to the bolt by the drilling apparatusexpands the nut in the competent strata, securing it therein, and bringsthe bearing plate into abutting contact with the roof surface of themine in a manner well known in the art.

it has heretofore been found advantageous to mount a roof drillingapparatus on continuous miners of the ripper bar type. Such mounting wasmade possible by the fact that the main body of the machine remainsstationary during that part of the mining cycle when the ripper bar isin operation. The mounting of the present invention makes the roofdrilling operation possible with such roof drilling apparatus mounted ona continuous miner of the boring arm type which is characterized bycontinuous forward motion of the miner during the mining operation.

A feature common to all continuous miners is the mounting of such minersupon orbital tread means known as crawlers, actuated by a crawler.mechanism having front and rear sprockets. The orbital tread means arecomposed of individual tread links which, as the machine moves forwardat a constant rate, move in the following manner: Each individual link,by action of the front sprocket, is laid upon the ground or othersupporting sur- 3,19%,bl l Patented Aug. 1t 1965 face and remainsstationary upon the ground while the machine moves forward resting aportion of its weight on such link; when the rearward portion of thecrawler mechanism passes over the individual link it is raised by actionof the rear sprocket from its position in contact with the ground andcarried forward in the direction of motion of the machine at a ratetwice as great as that of the machine; upon reaching the front sprocketof the crawler mechanism, the individual link is again laid upon theground and the above described cycle is repeated. It is to be noted thatthe motion of the above described tread link is an intermittent onecharacterized by periods of relatively rapid forward motion alternatingwith periods of time during which the tread link is stationary withrespect to the ground.

The present invention contemplates controlling the forward motion of atool mounting apparatus by taking advantage of the above describedaction of'crawler treads to impart a desired intermittent forward motionto such apparatus, i.e. periods of forward motion alternating withsubstantially equal periods of stationary positioning of the mountingapparatus. The roof drilling and'bolting apparatus may be mounteddirectly upon the tool mount ing which is carried forward by one of theaforementioned tread links or alternatively such apparatus may beslidably mounted upon the continuous miner but periodically heldstationary by the action of one of the tread links and intermittentlymoved forward on the miner by motor means mounted thereon.

The advantages inherent in the device of this inven tion are:

(1) Supporting the, roof bolting drill upon the tool mounting obviatesany need for an independent self propelled mechanism, to transport,position and control the drill.

(2) The tool mounting as described permits the drilling and boltingoperation to proceed without interrupting the mining operation.

(3) Positioning of the drill for correct spacing of the roof bolt isaccurately and readily achieved when the drilling apparatus isoperatively connected to the tool mounting of this invention.

(4) Such mounting permits the roof bolting operation to be applied verynear to the mining face so that only a small portion of the mine roof isleft unsupported at any time. This insures the safety of the miningoperation and makes it possible to use a boring type miner in mineralveins where the overlying strata is of such nature that roof conditionswould otherwise prevent the use of this type of miner.

(5) No mine personnel need be exposed to the risk of working under anunsupported roof.

It is therefore an object of this invention to provide a new andimproved mounting for a roof bolting drill.

his a further object of this invention to provide a new and improvedtool mounting applicable to a crawler tread propelled support.

Another object of this invention is to provide a new and improved toolmounting capable of imparting intermittent motion to a roof boltingdrill by operatively connecting such mounting to the crawler treads of acontinuous miner.

It is a more specific object of this invention to provide a new andimproved tool mounting, the forward motion of which is controlled by themotion of one tread link q) of an articulated orbital tread means whichsupports and renders movable over a surface a continuously movingcontinuous miner.

It is a further specific object of this invention to provide a new andimproved tool mounting for a continuously moving continuous minermounted upon orbital articulated tread means, which mounting providesthat the roof bolting drill will be alternately held stationary andcarried forward by one link of the orbital tread means.

It is a further specific object of this invention to provide a new andimproved tool mounting applicable to a continuously forward movingcontinuous miner, mounted upon orbital tread means so that intermittentstationary positioning of a roof bolting drill apparatus will becontrolled by the stationary positioning of one link of the orbitaltread means and the forward motion of the roof bolting drill apparatuswill be accomplished by the application of hydraulic power through asprocket and chain apparatus.

These and other objects and advantages of this invention willhereinafter become more fully apparent from the following description ofthe annexed drawings, which illustrate a preferred embodiment, andwherein:

FIG. 1 is a schematic representation of a continuous mining machineprovided with roof bolting drills supported by mountings constructedaccording to the principles of this invention.

FIG. 2 is an enlarged fragmentary elevational view of a crawlermechanism on which is mounted a roof bolting drill, which mounting isconstructed according to the principles of this invention.

FIG. 3 is a fragmentary side elevational view of a portion of thecrawler shown in FIG. 2 showing the roof bolting drill (in brokenoutline) in two different positions relative to the crawler.

1 16.4 is a sectional view taken substantially on the line 44 of FIG. 2.

FIG. 5 is a fragmentary side elevational view of a second embodiment ofa roof drill mounting constructed according to the principles of thisinvention.

FIG. 6 is a sectional view taken on line 6-6 of FIG. 5.

FIG. 7 is an enlarged fragmentary view partially in section of a portionof the apparatus shown in FIG. 5.

FIG. 8 is a side elevational view of the roof drill mounting of FIG. 2as applied to a crawler mechanism of a different type.

Referring now to the drawings: in FIG. 1 there is shown in dot and dashoutline a diagrammatic representation of a continuous miner 16supported, and rendered movable over a surface, by a pair of crawlermechanisms generally indicated at 12 provided with endless circulatingtread means 14 upon each of which crawlers 12 is mounted in a manner tobe described, a roof bolting drill 16. The dotted outline lit and 12"show the position of the continuous miner and crawler mechanism 12 withrespect to the roof bolting drill 16 (shown in solid outline) after thecrawler mechanism 12 has moved forward a distance approximately equal toone-half the length of the crawler mechanism from the position shown bythe solid outline 12.

In FIG. 2 there is shown a crawler mechanism 12 provided with endlessorbital tread means 14 trained about a front sprocket 18 and a largerdiameter rear sprocket 29. The tread means 14 is driven by the rearsprocket 2t actuated by a power means (not shown) to render thecontinuous miner 19 self-propelled and movable over a surface 21 in amanner well known in the art. The tread means 14 are composed of aplurality of individual ground engaging tread links 22 pivotablyconnected together in an endless chain by elongated cylindrical linkpins 24. A generally triangular bracket member 26 is mounted against anouter end surface of one tread link 22 by means of a pair of link pins24' somewhat longer than the link pins 24 used for the rest of the chainbut serving the same purpose of linking two of the tread links 22together. The special link pins 24' are rigidly secured in a pair ofbores centered in two of the corners of the bracket member 25, thesebores being laterally spaced by an amount equal to the spacing of thelink pin 24 in the rest of the chain. The bracket member 25 is mountedso that when the tread link 22 on which it is mounted is resting uponthe ground the bracket member 26 extends upwardly so that a threadedbore 23 (see FIG. 4) centered in the third corner of the triangularbracket member 26 will be at a distance from the supporting surface 21equal to the distance of the center of the front sprocket 18 from thesame surface 21. A generally U-shaped roof bolting drill mounting means36 is pivotably secured to the bracket member 26 by a generallytriangular mounting bracket member 32 overlappingly engaged with thebracket member 26 and pivotably engaged by a threaded retaining member34 such as a shoulder cap screw, threadedly engaged in the threaded bore28 and rigidly secured in such engagement by a threaded lock member 38such as a nut.

The U shaped roof bolting drill mounting means 3%) has a flattened bightportion 46 resting upon the surface 21 and a pair of upwardly extendingleg portions 42 and 44, being forward and rearward leg portionsrespectively, the upper ends of which are provided with a pair ofaxially aligned bores (not shown) which pivotably receive an elongatedcylindrical shaft element 41 (see FIG. 4). The shaft element 45 isrigidly secured to an intermediate portion of the roof bolting drill 16.The mounting means 36 thus provides a pivotable support for the roofbolting drill 16 to allow angle drilling by the roof bolting drill 16 ina manner to be described. The shaft element 49 extends forwardly throughthe leg element 42 and has mounted on the shaft 49, in keyedrelationship therewith, a lever element -8 suitably secured to the rodend of a double acting fluid actuated extensible cylinder 59' suitablysecured at its head end to a bracket 52 rigidly mounted on a lowerportion of the forward leg 42. Admission of pressure fluid to the headend of the cylinder 5%) will cause the roof bolting drill 16 to swinginto the position indicated by the line A in FIG. 4 while admision ofpressure fluid to the rod end of the cylinder 5t) will cause the roofbolting drill 16 to pivot about the shaft 4% and swing into the positionindicated by the line B in FIG. 4.

The roof bolting drill 16 is a type well known in the art and isprovided with a drilling tool 54 rotationally driven by a fluid operatedmotor 56 and is vertically advanced in a drilling operation by a drillfeed motor 58, also fluid operated. Another operation accomplished bythe roof bolting drill mechanism 16 is the operation of rotating andtightening the roof bolts (such operation being known as wrenching). Forfurther description of the operation and construction of such a roofbolting drill reference is made to U.S. Fatent 2,741,461.

In describing the operation of the device of this invention referencewill be made to the supporting surface 21 (the floor of a mine) and anupper surface 65) (the roof of the mine) both of which surfaces areproduced by the action of the continuous miner it) in disintegrating andremoving a portion of a mineral vein in a manner well known in the art.The continuous miner 10 associated with this invention is one which ischaractreized by continuous forward motion during the cutting,disintegrating and removal operations performed upon the mineral vein.The roof bolting drill 16 is shown in various positions identified inFIGS. 2, 3 and 4 as 16, 16', 16" and 16".

As the mining machine it? moves forward at a constant rate of speed eachindividual link 22 of the tread means 14 is deposited upon thesupporting surface 21 by the forward sprocket 18 and remains in theposition in which it was deposited upon the surface Zll until the rearsprocket 29 passes over it and raises it from contact with the surface21. The individual link 22 is then raised to the upper side of the rearsprocket 2t and moves forward with a speed approximately twice that ofthe forward motion of the miner 1@. When the individual link 22 reachesthe forward sprocket 1% it is again lowered to the ground and the cycleof motion is repeated. When such motion is applied to the bracket member26 pivotably supporting the roof bolting drill 16 through the roofbolting drill mounting means 31 the action of the roof bolting drill 16is as follows: a particular tread link 22 is associated with the bracketmember 26 by rigidly receiving therein the two link pins 24- upon whichthe bracket member 26 is rigidly mounted; when the link 22 is in theposition shown and identified as such in FIG. 2 the roof bolting drillwill be stationary with respect to the supporting surface 21 while themining machine It) and the crawler mechanism 12 move forwardly past it;the roof bolting drill will remain stationary and upright supported bysurface 21 until the link 22 reaches the position shown in FIG. 3; whilethe link 22' is traveling around the rearward half of the rear sprocketthe retaining element 34 will be traveling in a small semicircleconcentric with the sprockets 241; this motion of the retaining member34- will slightly raise the mounting bracket member 32 and in so doingwill change the position of the drilling device 16 from upright shown as16" to 'backwardly tilted shown as 16 in FIG. 3; as the link 22' travelsforwardly along the upper side of the crawler mechanism 12 it takessuccessive positions such as 22" shown in FIG. 2 with a concomitantpositioning of the roof bolting drill 16 shown as 16' in FIG. 2; whenthe link 22 reaches the front sprocket 18 the center of the retainingelement 34 will have been brought to a position coaxial with the frontsprocket 13; at this time the roof bolting drill 16 will be standingupright on the floor 21; as the mining machine 11 and the crawlermechanism 12 continue their forward motion the link 22' will bedeposited on the floor21 and remain stationary as before. It is to benoted that during the time the link 22' is resting on the supportingsurface 21 the roof bolting drill 16 is standing in a stationary uprightposition suitable for the accomplishment of the drilling operationdesired.

It is to be noted that while the roof bolting drill '16 remains uprightand stationary supported by the mounting means 39 resting on the surface21 suitable actuation of the rotative motor 56 and the feed motor 58 isused and applied to drilling tool 54 to produce a substantially verticalbore in the roof surface 60 extending from incompetent strata whichforms the roof surface into competent strata thereabove. When the borehas been completed the drilling tool 54 is withdrawn downwardlytherefrom. Insertion of a roof bolt into the bore and tightening of thebolt by the use of the rotative ability of the roof bolting drill 16 canbe accomplished as described in the introduction. The tightening of thebolt or wrenching is made possible by the use of the socket (not shown)added to, or substituted for, the drilling tool 54. Such activity isfeasible because the roof bolting drill mechanism 16 is stationary withrespect to the surface 21 and the roof surface 66 during the whole timerequired for the roof drilling and bolting operation.

After the drilling operation has been completed continued forward motionof the crawler mechanism 12 carries it past the drill 16 into therelative position shown as 15" in FIG. 3. Continued forward motion ofthe crawler mechanism 12 will first tilt the roof bolting drill 16 intothe position shown as 16" in FIG. 3 and then drag the roof boltingmechanism forward along the surface 21 at a rate substantially twicethat of the forward progress of the crawler mechanism 12. During theforward progress of the roof bolting mechanism 16 the mechanism passesthrough various positions similar to that illustrated at 16 in FlG. 2.It will be noted that as the roof bolting drill 16 approaches theforward end of the crawler mechanism 12 roof bolting drill 16 willgradually straighten up (that is become more nearly vertical). Furtherforward motion of the crawler mechanism 12 is without effect upon theroof bolting drill 16 until the rear sprocket again reaches the pointrelative to the stationary roof bolting drill 1d and the surface 21shown as lid" in FIG. 3. This cycle, consisting of a stationarypositioning alternating with relatively rapid forward motion of thedrill mechanism 16, crawler mechanism 12 continues to move forward asnecessitated by the mining operation.

Referring to FIG. 8 it is to be noted that the roof bolting drillmechanism 16 is here shown as it is applied to a crawler mechanism 62having forward and rear sprockets of equal diameters. The positions ofthe drill mechanism 16 indicated as 16a and 16c in FIG. 8 are actually asingle position with reference to the surface 21 and represent thestationary positioning of the roof bolting drill 16 as the crawlermechanism 62 moves forward relatively thereto. The position shown as 16bfor the roof bolting drill 16 represents a position taken by the roofbolting drill 16 as it is carried forward by the action of the link 22'as it travels toward the front portion of the crawler mechanism 62. Itis to be noted that the only difference in the action of the roof bltingdrill as shown in PEG. 8 from the action of the roof bolting drill asshown in i IGS. 2 and 3 reside in the fact that the roof bolting drill16 is not rearwardly tilted during part of the cycle, as shown in FIGS.2 and 3, but remains upright throughout the whole cycle of activity. Itis to be further noted that the same mounting means 311 and bracketmembers 26 together with the associated parts hereinbefore described canbe used for the mounting of this roof bolting drill 16 on either thecrawler mechanism 12 or the crawler mechanism 62.

In FIGS. 5 and 6 there is shown a second embodiment of this invention inwhich the crawler mechanism 12 is provided with a pair of formedoutwardly extended vertically disposed brackts 64 and 66, front and rearbrackets respectively, parallel to each other and longitudinally spacedwith respect to the crawler mechanism 12 so that the front bracket 64 isrigidly secured to the crawler 12 rearwardly adjacent to the frontsprocket 18 while the rear bracket 66 is rigidly secured to the crawler12 forwardly adjacent the rear sprocket 2d. The brackets 64 and asrigidly engage and support a pair of parallel, horizontally disposed,vertically spaced, cylindrical rail members 68. The rail members d8slidably support a U-shaped roof bolting drill mounting means '71similar to the mounting means 3% described in the case of the firstembodiment which similarly pivotably support the roof bolting drill 16as described with reference to FIGS. 2 and 3. The U-shaped mountingmeans 79 has a front leg element 7e and a rear leg element 73 connectedby a substantially fiat bight portion (9%. The leg elements 76 and 78are provided with pairs of extended portions 74 having hori zontal,axially aligned bores 72 (see FIG. 6) therein which slidably recive therails 68 to support the roof bolting drill 16 in longitudinally slidablerelationship with the crawler 12.

An elongated forwardly extending latch member 82 is pivotably mounted atthe lower end of the rear leg '78 and extends forwardly and downwardlyto abuttingly engage a cooperable latch element 84 rigidly mounted onthe outer surface of at least one of the tread links 22 of the orbitaltread means 14 so that motion of the mounting means 73 and the roofbolting drill 16 in relation to the crawler mechanism 12 may becontrolled by the cooperation of the latch member 82 and the latchelement 54 in a manner to be described. Pivoting motion of the latchmember S2 about its attachment to the rearward leg 78 is controlled by avertically disposed double acting fluid operated extensible cylinder 86pivotably mounted will be repeated indefinitely as long as the at itshead end by a suitable bracket 83 forwardly extending from an upperportion of the forward connected at its rod end to the forward end of helatcu of the latch member 32 to be raised out of engagement With thelatch element 84. Similarly the admission of pressure fluid to the headend of the cylinder will cause the front portion of the latch member 82to be lowered into a position suitable for engagement with the latchelement 8 (see FIG. 7).

In FIG. 7 there is also shown a fluid actuated rotary driving means $9provided with a suitable irive sprocket element 92 having teeth suitablyengaged with a chain element 94 trained about a considerable portion ofthe eriphery of the drive sprocket element 92 by the action of a pair oflaterally spaced roller elements located on either side of the sprocketelement 92. The chain element @4 extends from the forward bracket memberM to the rearward bracket member 65 being rigidly anchored in thebracket 65 and adjustably anchored to the bracket 64 by threaded members93 and 1635) so that s .itable tension may be maintained in the chainelement 94. The chain element 94 is located between and substantiallyequidistant from the rail members 68 and is parallel to the rail members63 except for that portion of the chain which at any particular momentis passing over the sprocket elements 92. Activation of the rotarydriving means 919 by the admission of pressure iluid thereto rotates thedrive sprocket element 2 and causes the mounting means 7% and the roofbolting drill to to move longitudinally with respect to the crawlermechani n 12. It is to be noted that numbers starting a 12 andcontinuing up through fill as applied in FIGS. 5, 6 and 7 identify partswhich are the same as those described in reference to FIGS. 1, 2, 3 and4 will not here be further described.

Operation of the second embodiment of this invention shown in FIGS. 5, 6and 7 is very similar to that of the first embodiment with the followingdifferences to be noted. Desired stationary positioning of the roofbolting drill 15 is accomplished as in the case of the first embodimentby connecting the mounting means 7% to a particular tread link 22positioned on the supporting surface 21 thereby securing the roofbolting drill 36 in a stationary position with respect to the supportingsurface 21 and the roof surface 6 1 while the miner ill and the crawlermechanism 12 move forward at a constant rate. The connecting of themounting means 'lll with the tread links 22, is accomplished by actionof the cylinder 36 in a manner hereinbefore described. Such latchingwill normally be accomplished when the link 22 upon which latch element84- is secured, is very near the forward end of the crawler mechanism 12having just been deposited on the ground by action of the forwardsprocket it As the roof bolting activity progresses, the crawlermechanism 12 will be moving past the mounting means '79 until the drilll6 approaches the position with respect to the crawler mechanism 12.which is shown solid in FIG. 5. At this time, the roof bolting operatinghaving been completed, the forward end of the latch member 32, lifted bythe cylindcr 36 in a manner hereinbelore described, will be raised outof engagement with the latch clement The sprocket element 92 activatedby the driving means and rotating in a counterclockwise direction asviewed in FIG. 7 will travel forwardly along the chain element B lcarrying the mounting means 76 and the drill forward along the crawlermechanism 12 until the mounting means 7% reaches a position near theforward end of the crawler mechanism 12 such as that shown in dottedoutline in FIG. 5. Upon reaching that position suitable activation f thecylinder as will renew the abutting engagement between the latch member32 and the latch element 34 at which time the cycle of operation beginsto repeat. lt

is to be noted that a plurality of tl c tread links 22 will be providedwith latch elements Sel The number and spacing of the latch elements 34will be determined in a particular instance by the desired spacing ofthe roof bolts to be installed by this device.

Having described a preferred embodiment of this invention in accordancewith the Patent Statutes it is to be realized that modifications thereofmay be made without departing from the broad spirit and scope of theinvention. Accordingly it is respectfully requested that this inventionbe interpreted as broadly as possible and be limited only by the priorart.

What is claimed is:

A tool mounting for a mine roof drilling apparatus comprising, a crawlerpropelled support movable over a surface, means secured to saidpropelled support for slidably supporting and orbitally guiding endlessflexible crawler treads for propelling said support, tool support meansconnected to said treads, drilling means secured to said tool supportmeans wherein said tool support means positions said drilling means inconstant engagement with said surface for forming holes in such mineroof, and means cooperable at least when one of the tread plates issurface engaged for maintaining said drilling means stationary when saidpropelled support is moving relative to such surface.

2. A mobile support movable in a passageway comprising, laterally spaccdcrawler treads secured to said support for moving said support in suchpassageway in response to the orbital movement of said crawler treads ina closed path, connecting means secured to a link of said crawlertreads, a U-shaped cradle pivotally connected to said connecting meansand having a portion thereof in constant engagement with the floor ofsuch passageway as said treads are orbited in such path, and a drillingtool supported by said cradle and being positionable to form holes inthe roof of such passageway when said link to which said connectingmeans is secured and engaged with the floor of such passageway.

3. In combination, crawler treads engageable with a surface, means formoving said crawler treads in a closed predetermined orbit, a toolsupport, means for cooperably connecting said tool support to saidcrawler treads so that said tool support is advanced along the line ofmovement of said crawler treads with such advance consisting ofalternate periods of repose and movement, said means includes a linkmember secured to a tread of said crawlers with a portion of said linkextending Within such closed orbit and to which said tool support ispivotally connected, and said tool support being of a length toconstantly engage said surface.

l. A mobile support movable in a passageway comprising, laterally spacedcrawler treads secured to said support for moving said support in suchpassageway in response to the orbital movement of said crawler treads ina closed path, generally triangularly shaped, connecting means beingsecured to a link of said crawler treads and having a portion thereofextending interiorly of such path, a U-shaped cradle pivotally connectedto said portion of said connecting means and having a portion thereof inconstant engagement with the floor of such passageway as said treads areorbited in such path, and a drilling tool connected to said cradle andbeing positionable to form holes in the roof of such passageway whensaid link to which said connecting means is secured and engaged with thefloor of such passageway.

5. A drilling apparatus bodily movable over a surface comprising, anelongated movable support having transversely spaced crawler treadframes secured thereto, said tread frames having a continuous orbitdefining guide surface comprising coextensive rectilinear portionsconnected by arcuate portions, a plurality of pivotally connected treadmeans for forming an endless flexible crawler tread chain which ismovably disposed on said tread frames respectively, connecting meanssecured to one of said tread means and having a portion extendingintermediate said rectilinear and said arcuate portions, a drillingapparatus pivotally connected to said portion of said connecting meanswith a portion thereof in constant engagement with the surface overwhich said tread means engages, means for circulating said crawler treadchains about their respective guide surfaces of said tread framesrespectively for moving said support over a surface, Whereby saiddrilling apparatus remains stationary when said one of said tread meansis engaged with such surface.

References Cited by the Examiner UNITED STATES PATENTS Craig 180-8.9Nardone 172-95 McLemore 111168 Gunning 175l68 Ruth et a1 175-168BROUGHTON G. DURHAM, Primary Examiner.

CHARLES E. OCONNELL, Examiner.

1. A TOOL MOUNTING FOR A MINE ROOF DRILING APPARATUS COMPRISING, ACRAWLER PROPELLED SUPPORT MOVABLE OVER A SURFACE, MEANS SECURED TO SAIDPROPELLED SUPPORT FOR SLIDBALY SUPPORTING AND ORBITALLY GUIDING ENDLESSFLEXIBLE CRAWLER TREADS FOR PROPELLING SAID SUPPORT, TOOL SUPPORT MEANSCONNECTED TO SAID TREADS, DRILLING MEANS SECURED TO SAID TOOL SUPPORTMEANS WHEREIN SAID TOOL SUPPORT MEANS POSITIONS SAID DRILLING MEANS INCONSTANT ENGAGEMENT WITH SAID SURFACE FOR FORMING HOLES IN SUCH MINEROOF, AND MEANS COOPERABLE AT LEAST WHEN ONE OF THE TREAD PLAES ISSURFACE ENGAGED FOR MAINTAINING SAID DRILLING MEANS STATIONARY WHENSASID PROPELLED SUPPORT IS MOVING RELATIVE TO SUCH SURFACE.